Abstract. The influence of second-generation products on the particle mass yield of
β-caryophyllene ozonolysis was systematically tested and quantified.
The approach was to vary the relative concentrations of first- and
second-generation products by adjusting the concentration of ozone while
observing changes in particle mass yield. For all wall-loss corrected organic
particle mass concentrations Morg of this study (0.5 < Morg
< 230 μg m−3), the data show that the particle-phase
organic material was composed for the most part of second-generation
products. For 0.5< Morg < 10 μg m−3, a range which
overlaps with atmospheric concentrations, the particle mass yield was 10 to
20% and was not sensitive to ozone exposure, implying that the
constituent molecules were rapidly produced at all investigated ozone
exposures. In contrast, for Morg > 10 μg m−3 the
particle mass yield increased to as high as 70% for the ultimate yield
corresponding to the greatest ozone exposures. These differing dependencies
on ozone exposure under different regimes of Morg are explained by a
combination of the ozonolysis lifetimes of the first-generation products and
the volatility distribution of the resulting second-generation products.
First-generation products that have short lifetimes produce low-volatility
second-generation products whereas first-generation products that have long
lifetimes produce high-volatility second-generation products. The ultimate
particle mass yield was defined by mass-based stoichiometric yields αi of α0 = 0.17 ± 0.05, α1 = 0.11 ± 0.17, and α2 = 1.03 ± 0.30 for
corresponding saturation concentrations of 1, 10, and
100 μg m−3. Terms α0 and α1
had low sensitivity to the investigated range of ozone exposure whereas term
α2 increased from 0.32 ± 0.13 to 1.03 ± 0.30 as
the ozone exposure was increased. These findings potentially allow for
simplified yet accurate parameterizations in air quality and climate models
that seek to represent the ozonolysis particle mass yields of certain classes
of biogenic compounds.